Arcing ground suppressor



July 4, 1933. F, w, GAY

ARCING GROUND SUPPRESSOR Filed Dec. l1, 1950 2 Sheets-Sheet 1 INVENTOR July 4, 1933. F. w. GAY 1,916,926

ARCING GROUND SUPPRESSOR Filed Dec. 11, 195o 2 sheets-snm 2 FICT.

INVENTOR l w FIG. G BMM Patented July 4, 1933 FRAZEJR'4 W. GAY, OF NEWARK, NEW JERSEY y ARCING' GROUND SUPPRESSOR Applicatonledf December 11, 1930. Serial No. 561;@08.

This invention relates to ai novell tnansmission system havingfnherently aV higher transmission capacity and a greater reliability of operation than-l systems commonly used'` heretofore, and) inr addition a systemA havingL its said phase in orderto allow the `groundingarcztoclear-up.

It is a further object of'this inventionto provideA ailow'reactancezpercircuit onta transmission line; f

It is a: further object ofy this: invention to provide a. novel' relay system capable of se- I'ecting a phase circuit that is in trouble.

I't is a further:` object of this invention to substantially instantaneouslyclear a phase of a transmission line that is in vserious trouble-I Y I propose to carry-twin-conductors in each phase of each transmission line and to insuf latefrom each other-eachconductor in such twin pair of conductors. It is well known that a major part of the reactance voltage built up in a single phase conductor is produced` byr flux interlinkages that occur withina few inches of' the conductor and that if the diameter of the condluctor is considerably increased` as by the use of aluminimiinstead of copper, a substantial reduction in impedance occurs even if the resistance lof the conductor is not materially altered. `By using a plurality of conductors in each phase of a transmission line and. by spacing each of the conductors far apart with respect t0 any other conductor, I greatly increase the reluctance actin-g against magnetism linking such conductors and hence greatly reducethe reactance. New itis welly known that the capacity of a long high volt-age transmission line having conductors of lar-ge cross section is limited by the reactance of]v theline rather than by its resistance. I find thatiby using two conductor-s per phase insulated from each other and spaced apart several-feet as I propose, I can increase the-capacity of such a high voltage three phase transmission line from 3()y to 40%. Many power companies willind that the construction I- suggest may profitably be used by reason of increased line capacity even if the many other advantages I obtain did not follow with Very little additional' expenditure. l Up tothe presenttimeonly one method of substantially instantaneously selecting a faulty :transmission line has proved. even moderately reliable, simple7 and cheap and 70 this is the system using two parallel .transmission lines and diiiercntial relays function.- ing' on a; difference in current between them. This systemis reliable for .faults nearv the center of the line but if the faultis near one end the current in. each: line is nearly equal and the relays atlthe remote end may not function until the breakers near the fault have opened and limited the fault current to a single line. I propose to use mid tappedtransformers shunted across each pair of twin lconductors atboth ends of the line and with asingle conductor feed at the mid poi-nt of the auto transformer. such a system will unbalance the currents and build up a Voltage across the, transformer. A secondary coil on the core will have v induced in it a high voltage and will operate an inverse time load relay on the aected phase substantially instantaneouslyA for great current imbalance. I propose in the preferred form touse al so called hedge hog transformer (havin-g open magnetic circuit), so that the voltages induced will not reach a maximum except for a simultaneous failure of lines on different phase circuits.

I propose toi connect all transformers feedingy power to my novel transmission system so thatV they will perform as fully -explained' in A100 A fault on one conductor of 85 ymy Patent No. 1,7 52,666 anda fault onv one phase will cause a very limited'amount of phase to ground current imbalance and a comparatively low induced voltage on the inl verse time relay and hence a relatively long .time of relay operation, while if a fault rent and would be so great that the inverse time load relays would function substantially A instantaneously.

lio

' pole circuit breakers, each functioning inde- It is evident therefore that for a line to ground fault the line will in most cases be able-to vextinguish an arc caused by lightning or aswitching serge before the relatively small unbalanced current' causes the relay on the 'grounded line to operate to trip the line and before any kinsulator strings are damaged. n In addition to limiting the fault to ground current `to a value which should clear up without assistance, I propose to add a low voltage winding on each phase of a main star-star connected transformer banlrg and connect ,a switch across eachv such winding with relays ladapted to hold a short circuiting switch closed (for a fraction of a second) to short circuit that transformer ph ase winding connected to the faulty phase circuit. is obvious that the short circuiting` of this transformer will instantly bring the faulty line to substantially ground potential.

It is a further object of this invention to combine'single phase switching with a thoroughly reliable means for selecting the individual phase conductors that are faulty.

lt is important to note that most original three phase circuits were controlled by single pendently of the others. y

This method of control was abandoned for two reasons.

1st. The more extensive use of three phase Vmotors made itundesirable tol leave the machines "on single ph ase.

" 2nd.- lWhere twoor more three ph ase lines were in multiple, norelays were available to reliably select the faulty phase, although such relays were availableto reliably select a faulty three phase line.

, rlhe use of aplurality of three phase circuits in multiple and the loading of such aplu'rality ofmultiple circuits to their stability limitmakes it imperative to maintain Aa minimum reactance for such a plurality of three phaselines. vThe interrupting of vall three'pliases of one such line enorvmously increases the reactance of a group of two or three lines and diminishes their ability to transmit power much more than the interrupting of only one phase of one such a line'.` y

y22, es,

l). C. trip circuit 31, 32.

Referring to the drawings, Figure 1 shows a three phase sending bus and a three phase receiving bus and one f three phase connecting line with twin conductors'and single phase switching. i Figure 2 is a detail of one of the three phase arcing ground Suppressors of Figure 1 i. e.

. Figure 3 `shows a detail of one of the auto 'transformers of Figure l.

ing conductors 1, 2, 3. This bus is-connected to yathree' phase substation vbus having conductors 4, v5, 6i by the' novel three phase transmission system `ofthe present invention.

.7, 8, k9iare three auto transformers preferably suspended on. a pole at the station end of therline.v rlhe -niid points of the windings 'of these auto transformers 7, 8, 9 are connect-ed by leads 13,14, 15 to busses 1, 2,3.l Single pole circuit breakers 16, 17, 18 are" connected in these leads 13, 14,15 and are tripped fby coils 19, 20, 21. Secondary' coils 24 are in inductive relation tothe primary coils 7,' 8, 9 ofthe auto transformyers at the station end. These auto transformer secondaries connect to relays 25, 26, 27. These relays`25, 26, 27 upon voperation close switches 28', 29, 30.` Switches 28,29, 30 connect trip coils v19, 2O,`

circuit is' energized by closing switch 33.

Auto transformers 10, 11, 12 similar ito 7, 8 9 are referabl sus `acnded on a nole at the substation end ofthe line.v The mid points lof thesev auto transformers yareconnected-to the substation bus 4, 5, 6 by conductors 40,41, and 42 through single phase .circuit breakers 43.,V 44, 45.

v-Tl ese :circuit breakers are operated by trip coils 46, 4'?,y 48. Secondary windings 49, 50, 51are `wound in inductive relation `to the auto transformer coils 10, 11, 12 and are connected respectively to the relays 52,53, .54;v These relays 52, 53, on operation close respectively switches 55, 56, 57. Switches 55', 56, 57 upon closing connect trip coils 46, 47, 48 to D. C. trip circuitsl 58, 59. The end terminals of the autotransforiner at the station end are connectthe attached drawings rshows 'a high voltage three phase station bus'hav- 21 respectivelyk to This D. C. trip' ed tofthe end terininals'of auto transformerVM 'winding 10. at ythe substation endA by Vtra-nsinission conductors 34 and 35 of 4one phase. Similarconductors 36 and 37 connect the end t .rmi-nais of transformers 8 and 11 to form the 4secondphase and similar conductors 38 land 39 connect; the vend terminals of transformers 9 and 12` to form the third phase of the transmission. vThe station bus 1, 2,' 3 receives its power from transformer windings 61', 62, 63 through leads 64, 65, 66 connecting to the bus through circuit breaker 60. The neutral ofl the transformer windings 61, 62, 63 is connected to ground by lead 67. Generated power is ,ted to thetransformer primaries 68, 69, 70. Low voltage tertiary windings 71, 72, 73 .arer connected to shortrcircuiting devices 74, 75, 76A by neutraV lead 77 and main leads 78, 79, and 80;

F igure2 shows one of the short circuiting devices (7,6V of Figure 1') `.connected acrossthe'winding 73 by neutral leads 77 and Winding lead 80. This short circuiting device or arcing ground suppressor 76 similar to shortcircuiting devices 74 and 75;. A relay. 81-has its operating coilconnected across winding.. 73 by neutral lead 77 and phase lead 80.` This relay 81 uponv operating closes switch 82. Switch 82 connects motor 83.-'across the D. C. circuit 31, Motor E53-drives a drum 84through shalt 85. This drum 84 carries aconducting member 86 which bridges brushes 87 and 88 and eneri .gizes contacter coil 89 from D. C. circuit 31,

32. Theenergizing of coil 89 closes switch 90. Switch 90 short circuits windingv 7-3 and thewvoltage therefore of inductively connected windings 63, 7-0, and 73 substantially vanishes and conductor 3 is brought to sul stantially the sarnepotential as 4ground lead 67..

Figure 3 shows an elevation partly in section of the auto transformerprimary 7` of `Figure 1. This auto 'transformer is-a+- tached toa support 104 at the top: of transmission line tower at the sending end.v The conductor13 is attached to the tower support 104 by means oi an insulator string` 101 and the transmissioncables 34 and 35 are attached to the support 104 byinsulators 102 and. 103.. The. primary winding 7 is'wound with one'halfits turns ineach of two concen tric coilsv 7f, 7. The mid .poi-nt is connected to lead 13 andthe ends of the winding to transmission cables 34 and 35. Coils 7, 7 are mounted on a porcelain insulator 113 which is attached to linsulator 1.15, which in turn is lattachedto the steel support 104. A magnetic core 111 is mounted inside porcelain insulator 113 and on this magnetic core` is wound the secondary coil 22. An electrostatic shield 116 iswrapped `around coil 22. This-shield as well as core 111 is grounded by lead 1117 to thc tower support104. [rd-` ditional4 insulation 114 is supplicdbetween thegrounding shield 116 and the porcelain f Figure 4'shows a conductor of the .pres ent ,inventionin cross section and Figure shows'a longitudinal cross section of the same preferred conductor. Steel wires 1 to .7

' constitute lthe center core which acts as a messenger cable. Around ythis messenger cablea metal wire or tube 851s wound sp1ral` ly. Outside of this meta-l tube the aluminum cables having a largeconducting diameter are desirable. y 1

l Figure 6 A,shows a. cross section of the two conductors34and 35 and itwill be seen` at once thatthe magnetic reactance flux interlinlring a single conductor and hence meet ing low'- reluctance embraces only one half the current, while that magnetic linx which `interlinls the total current and therefore is subject to double the M. 'M. F, is opposed by the reluctance of long liuxpath.. l

. The operation of this device is as follows. If a fault develops on any `conductor asat X, say on conductor 39 (say conductor 39 is grounded as by` Va lightning flash). The grounding of conductor 39 effectively grounds station bus 3, transformer lead 66, and short circuits high voltage 'winding 63. The other two high` voltage windings 61 and 62 carry the load in open delta, as fully eXT Aplained in my APatent No. 1,752,666. The high magnetizing current of `the open del-ta transformer,` as [well as any additional ground current that may be caused to flow, astully'explained in my Patent No. 11,752,666y will passt-o the ground through the fault at 'X and over leads 15- andv39. This4 current will pass only through the bottom half` of auto transformer vwindings 9. The corev of transformer 9 will be magnetized and a voltagewill bel induced in secondary windingr24. This will causerelay 27 to move itscont-acts at a slow rate of speed. yRelays 25 to 27' and 52 to 54 are. of the inverse ltime element type which, as is well known to those skilled in'v the art,.areoperated by induced currents and i are damped by a permanent magnet, thereby resulting in slow operation of theserelay on the occurrence of small overloads. v. Immediately upon the occurrence of `the 'fault at X and the consequent short circuiting of transformer windings 63, 70, and 73 devicef76 will proceed to operate. is shown in detail in Figure 2. A relay..81 (Figure 2) has a holdingcoil shunted across leads 77 and 80 that is across winding v73. Immediately upon failure of voltage of windl ing 73, relay 81 allows switch 82 to close. This placesmotor 83-across the D. C. circuit 31, 32. Motor 83revolves drumv 84through shaft 85. Contact 86 bridges brushes 87 and 88 and places coil 89 across D. C.. circuit-31,

32. Coil 89 thereupon closes contactorf90 and contacter 90 `places a short circuit across tertiary winding 73.y I The short-circuiting of winding 73 acts also to short-circuitwindings 70 and 63, thereby reducing the voltage. across the fault at X to substantially Zero Device 76 r12e y tially the same voltage so that the ground wire 67 accepts the charging current ofthe line. The' fault at X' will clear up (unless line 39, is solidly grounded) while contacter 90 is close-di. e. during the time that the contact 86 ondrum. 84 is bridging brushes 87 and 88. Y C

4After the fault at X cleai's up, voltagewill appear across windings 63, 70, and 73 the inomentcoil 89 is open circuited andV in consequence contactor 90 opens the short circuit across winding T 3. Relay 81 will open switch 8:2 almost vthe instant that voltage appears on wires 77' and 80. Motor 83 is highly damped and will stop almost instantly after Contact l86 leaves'brushes 87 and 88. Equipment 76 is thus reset and ready for another fault. If lthe fault at X isnot removed by the operation of apparatus`76, switch 82 will remain closed and motor 83 will continue to rotate andcontactor QQ will pump until relay 27 operates. Relay 27 may be set to operate aftercontactor 90 opens the first time and before it closes the second time, so that switch 90 Vwill not pump. Obviously if the closing of ,contactor 90 removesr the fault at X, relay 27y will slowly reset and breaker ,18l

will notA trip. ,e

On thek other hand, if a simultaneous fault occurs on any other line in a different phase,y

the current passing through fault 'X will be man'y'tiiiiesV as great as for Va'siinple ground at X,'so` that relay 27 will trip breaker 18y alinost instantly and before contactor 90 can operate the first time.

As Vmany changes could be made in the' Aabove construction and many apparently widely diiferentembodimeiits of this invention could be made without departing from the scope thereof, it is intended that all matterfcontained in theabove descripion or shown in the accompanying drawings shall be'interpreted as illustrative andk notin a limiting sense.,

`That is claimed" is: n

1. 'ln combination in a three phase transmission system fed by a transformer winding having a solidly grounded neutral, a switch arranged enclosing to bring` one phase of said transmission system to ground' potential during a'predetermined short interval olf time, va conductor connected;l to said phase through circuit interrupting means, re-

lay -means cooperating with vsaid switchand arranged upon `the occurrence of aground onsaid conductor to rmaintain v'said' switch lin a closed'position during a predetermined period of time and relay `means operating upon the occurrenceof said ground and adapted' to causethe tripping of said circuit interrupting means following the eX- piration of said 'predetermined periodi of time.

2. In combination, in a transmission system,a three phase sending bus, ya three phase receiving bus, three-midtappedv auto transformers adjacent said sending bus, three inidtapped auto transformers 'adjacent said receiving bus, each of said auto transformers adjacent said sending bus having its mid-tap connected to a respective one vlof the phases of said sending` bus land each of said auto transformers adjacent said receiving bus havingy its mid-tap connected to a respectiveone of the" phases of said'receiving bus, a plurality of line conductors arranged in pairs, each pair of line conductors having oneof their terminalsconnected to lthe ends of' a respective one of said auto transformers adjacent tlie sending bus and the other of their terminals rconnected to the ends of a respective one lof said auto transformers adjacent the receiving bus, single pole circuit breakers included respectively in the connection,

between each of said sending bus transformers and the sending'bus and in the connecranged upon the occurrence of a fault on one conductor of a pair of transmission line conductors to effect the tripping of the circuit brealters in circuit with said faulty conductor. V

3.1In'combination, in a three phase transmission system,l a three phase `transformer bank i with star connected highy voltage winding having three phase windings and a solidly grounded neutral, means adapted upon the grounding of one phase line of said transmission system to limit thevfault to groundcurrent to a predetermined vrelatively vsmall value, three low voltage tertiary windings, each of saidlow voltage tertiary windings being inductively associated with a" respective phase winding of said high voltage transformer winding,and switch meansconnected -to short-circuit one of saidlow voltage tertiary windings upon the grounding of the phase line connected to its inductively associated hich voltage transformer phase winding. i w V' f v.

\ 4. In combination, in a threev phase transmission system, a three phase transformer bank with a star `connected high voltage vwinding having three phase windingsand a solidly grounded neutral, said transformer bank high voltage winding being'connected to said transmission system and arranged to operate'open delta upon thev sho-rt-cireuiting of one 0f its phase windings, a short-circuiting device connected across the terminals of one of the phases of said transmission system `and operable upon closing to short-1` circuit said phase, and a relay operable upon the reduction of voltage on said phase `to cause the operation of said short-circuiting device.

5. In combination, in a three phase transmission system, a three phase transformer bank With a star connected high voltage Winding having three phase Windin gs and a solidly grounded neutral, said high voltage Winding being connected to said transmission system and arranged to operate open delta upon the short-circuiting of one of its phase windings, a short-circuiting device connected across the terminals of one of thephasjes of said transmission system and operable upon closing to y vention set 'forth above I have hereunto set day of December, 1931.

my hand this 10th FRAZER W. GAY. 

